Expression data of pmr1 mutants

The yeast PMR1 (ATP2C1) gene codes for the eukaryotic prototype of a high affinity P-type ATPase required for Ca2+/Mn2+ transport into the Golgi. Cells lacking PMR1 exhibit multiple genetic interactions with genes involved in DNA recombination and replication, a fact that is not yet understood. We find that deletion of PMR1 causes a delay in DNA replication initiation, progression and G2/M transition and induces the transcriptional up-regulation of genes involved in cell cycle regulation, including CLB5 and SWE1. Interestingly, pmr1 clb5 double mutants exhibit a dramatic delay in DNA replication and increased DNA breakage, while endoreplication and the formation of multi-nucleated, giant yeast is observed in pmr1 swe1 cells. Because these phenotypes can be attributed to impeded Mn2+-pump function, we provide a model in which Mn2+ interferes with Mg2+ in the nucleus, and vice versa, Mg2+ interferes with Mn2+ in the Golgi. Consequently, cell cycle progression is challenged by aberrant catalytic activities of enzymes involved in replication and protein glycosylation.

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García-Rodríguez N, Díaz de la Loza Mdel C, Andreson B, Monje-Casas F, Rothstein R, Wellinger RE